Chapter 9 - Hydrogen

What mass of hydrogen peroxide will be present in 2 litres of a 5 molar
solution? Calculate the mass of oxygen which will be liberated by the
decomposition of 200 mL of this solution.

Assertion (A) : Some metals like platinum and palladium, can be used as
storage media for hydrogen.
Reason (R) : Platinum and palladium can absorb large volumes of
hydrogen.
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Exemplar Problems, Chemistry 122
(i) Statements A and R both are correct and R is the correct explanation of A.
(ii) A is correct but R is not correct.
(iii) A and R both are correct but R is not the correct explanation of A.
(iv) A and R both are false.

In the following questions a statement of Assertion (A) followed by a statement
of Reason (R) is given. Choose the correct option out of the options given
below each question.

Assertion (A) : Permanent hardness of water is removed by treatment with
washing soda.
Reason (R) : Washing soda reacts with soluble magnesium and calcium
sulphate to form insoluble carbonates.
(i) Statements A and R both are correct and R is the correct explanation of A.
(ii) A is correct but R is not correct.
(iii) A and R both are correct but R is not the correct explanation of A.
(iv) A and R both are false.

Match the items in Column I with the relevant item in Column II.
Column I Column II
(i) Hydrogen peroxide is used as a (a) zeolite
(ii) Used in Calgon method (b) perhydrol
(iii) Permanent hardness of hard (c) sodium
water is removed by hexametaphosphate
(d) propellant

Match the terms in Column I with the relevant item in Column II.
Column I Column II
(i) Electrolysis of water produces (a) atomic reactor
(ii) Lithium aluminium hydride is used as (b) polar molecule
(iii) Hydrogen chloride is a (c) recombines on metal
surface to generate high
temperature
(iv) Heavy water is used in (d) reducing agent
(v) Atomic hydrogen (e) hydrogen and oxygen

What happens when BaO₂ is treated with phosphoric acid?

What happens when hydrogen peroxide reacts with acidified K₂Cr₂O₇?

Calculate the strength in volumes of a solution containing 30.36 g/l of H₂O₂.

What is the volume strength of 2M-H₂O₂?

Why is hydrogen peroxide stored in wax-lined glass or plastic vessels in
dark?

Hydrogen peroxide acts as oxidizing agent as well as a reducing agent. Why?

What do you mean by 100 volume of hydrogen peroxide?

What happens when H₂O₂ reacts with ethylene? [

What happens when H₂O₂ reacts with acidified KMnO₄?

Why is H₂O₂ a better oxidant than water?

How many hydrogen – bonded water molecule are associated in CuSO₄. 5H₂O?

What is calgon?

Why is water an excellent solvent for ionic or polar substances?

Why does hard water not form lather with soap?

Why is ice less dense then water and what kind of attractive forces must be
overcome to melt ice?

Show with reaction the amphoteric nature of water.

How does H⁺ ion forms hydronium ion (OH₃+) in water?

Define hard water.

Write the Name of a zeolite used in softening of hard water.

Give a reaction in which water acts as an oxidizing agent.

Which gas is produced on electrolysis of ionic hayride?

What are the characteristic features of ionic or saline hydrides?

What is the geometry of the compound formed by group 14 to form
molecular hydride?

What happens when sodium hydride reacts with water?

What is the behavioral similarity between NH₃, H₂O HF compounds?

Give an example of electron – deficient hydride.

What happens when water is added to calcium hydride?

Give an example of each of an ionic hydride and a covalent hydride.

What are hydrides?

Name the categories into which hydrides are categorized

Which fuel is used as a rocket fuel?

What is understood by hydrogenation?

How can the production of dlhydrogen obtained from ‘coal gasification be
increased’?

How can the production of dlhydrogen obtained from ‘coal gasification be
increased’?

How is ammonia prepared using dihydrogen?

How is methrol prepared using dihydrogen?

What is the pH of water?

Why is dihydrogen gas not preferred in balloons?

What is water – gas shift reaction?

Give the commercial method of preparation of dihydrogen.

Give the laboratory method of preparation of hydrogen

What is coal gasification?

What is syn-gas?

Give the main characteristics of isotopes.

Give the main characteristics of isotopes.

Name the isotopes of hydrogen.

Why does hydrogen occupy unique position in the periodic table?

Give the electronic configuration of hydrogen

Which isotope of hydrogen
(i) does not contain neutron?
(ii) is radioactive?

How does H₂O₂ behave as a bleaching agent?

Do you expect different products in solution when aluminium(III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equations wherever necessary.

What do you expect the nature of hydrides is, if formed by elements of atomic

numbers 15, 19, 23 and 44 with dihydrogen? Compare their behaviour towards

water.

How can saline hydrides remove traces of water from organic compounds?

What is the difference between the terms 'hydrolysis' and 'hydration'?

Knowing the properties of H₂O and D₂O, do you think that D₂O can be used for drinking purposes?

What properties of water make it useful as a solvent? What types of compound can it (i) dissolve, and (ii) hydrolyse?

Describe the usefulness of water in biosphere and biological systems.

Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful?

What is meant by 'demineralised' water and how can it be obtained?

Write chemical reactions to justify that hydrogen peroxide can function as an oxidizing as well as reducing agent.

Write chemical reactions to show the amphoteric nature of water.

Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.

What causes the temporary and permanent hardness of water?

Describe the structure of the common form of ice.

Consider the reaction of water with F₂ and suggest, in terms of oxidation and reduction, which species are oxidized/reduced.

What do you understand by the term 'auto-protolysis' of water? What is its significance?

Compare the structures of H₂O and H₂O₂.

Arrange the following

(i) CaH₂, BeH₂and TiH₂in order of increasing electrical conductance.

(ii) LiH, NaH and CsH in order of increasing ionic character.

(iii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.

(iv) NaH, MgH₂and H₂O in order of increasing reducing property.

Saline hydrides are known to react with water violently producing fire. Can CO₂, a well known fire extinguisher, be used in this case? Explain.

Among NH₃, H₂O and HF, which would you expect to have highest magnitude of hydrogen bonding and why?

How does the atomic hydrogen or oxy-hydrogen torch function for cutting and welding purposes? Explain.

How do you expect the metallic hydrides to be useful for hydrogen storage? Explain.

What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.

Do you expect the carbon hydrides of the type (C_nH_{2n+ 2}) to act as 'Lewis' acid or base? Justify your answer.

What characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reactions?

What do you understand by (i) electron-deficient, (ii) electron-precise, and (iii)electron-rich compounds of hydrogen? Provide justification with suitable examples.

Discuss the consequences of high enthalpy of H-H bond in terms of chemical reactivity of dihydrogen.

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

How can the production of dihydrogen, obtained from 'coal gasification', beincreased?

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

Write the names of isotopes of hydrogen. What is the mass ratio of these isotopes?

Justify the position of hydrogen in the periodic table on the basis of its electronicconfiguration.